The head of the hex bolt has a cross hole and a flat washer on the blank part of the bolt neck, and a spring washer is built into the "apset" bolt. Common names are referred to as "Apset Hex Bolt(P3)" and "Apset Bolts" It is suitable for preventing the risk of the washer falling off during tightening work. Use it for tightening limited spaces and other areas to improve work efficiency. This product is manufactured by a Japanese manufacturer.